The Bondi case is a reminder that Trump, who is fond of calling his Democratic opponent "Crooked Hillary" Clinton, has a batch of serious ethics issues of his own.

Like many of Trump's problems, the Bondi flap is an outgrowth of the ill-fated Trump University, a now-shuttered operation that claimed to teach real estate secrets to students. The for-profit company has drawn condemnation, fines and lawsuits from coast to coast.

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NYT: Trump donation violations decades long

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NYT: Trump donation violations decades long03:08

In addition to suits filed by former students who claim they were ripped off, Trump drew the attention of attorneys general in Texas, Florida and New York who investigated whether the gap between what the school promised and what it delivered constituted fraud.

But only one state, New York, has advanced its prosecution to the point of a trial, expected to take place after Election Day.

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"Thousands of people were bilked out of millions of dollars. Our first priority is to get their money back and to re-establish the legitimacy of educational institutions in New York state," is how Attorney General Eric Schneiderman described his case against Trump, whom he calls "someone who was absolutely shameless in his willingness to lie to people, to say whatever it took to induce them into his phony seminars."

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Trump charity's donation to Florida AG questioned

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In Texas, then-Attorney General Ken Abbott (who is now governor) spent more than a year investigating Trump University -- but the case ended without prosecution when Trump decided to close up shop in Texas, over the strenuous objection of staffers who wanted Trump sued and/or fined for $5.4 million. One staffer, John Owens, the state's deputy chief of Consumer Protection, later said he was overruled on the case for political reasons -- an allegation that took on more meaning when records showed that, three years after the case was dropped, Trump donated $35,000 to Abbott's successful campaign for governor.

A similar pattern played out in Florida, where it turned out that Bondi personally solicited a donation from Trump -- and received a $25,000 donation in 2013 -- at the same time her office was considering whether to press ahead with fraud allegations against Trump University. Bondi ultimately decided not to take action; a spokesman told CNN that New York's prosecution "would provide relief to aggrieved consumers nationwide," making a Florida prosecution unnecessary.

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Trump defends donation to Florida attorney general

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Trump defends donation to Florida attorney general 02:45

A deeper dig into Trump's past shows yet another prosecutor who seems to have taken it easy on the billionaire -- and received a needed political donation in what might be a coincidence, or might be pay-to-play.

According to Wayne Barrett, a prize-winning investigative reporter who has written two books about Trump, the businessman sold two apartments in Trump Tower in 1988 to a shady character named Robert Hopkins, who would ultimately land in prison for running a massive illegal gambling operation. Hopkins, according to Barrett, brought $200,000 in cash to the closing for his apartments, which Trump attended; the money was ferried to the bank in a Trump limo.

That caught the attention of then-US Attorney Rudy Giuliani, who dispatched a top assistant to dig into the case and see if Trump was participating in money laundering for the mobster. Giuliani dropped the investigation -- and a year later, Trump was a co-chair of his campaign for mayor, raising $41,000 for him.

Trump himself has acknowledged that his political donations aren't charity. "As a businessman and a very substantial donor to very important people, when you give, they do whatever the hell you want them to do," Trump told the Wall Street Journal last year.

That, in turn, raises the question: What did he want Bondi, Abbott -- and, for that matter, Rudy Giuliani -- to do for him? And what steps, if any, would he take to end a system that apparently allows businessmen to buy prosecutors and other officials so freely?